Release 0.2.0

Added

• WakuRelay.getPeers method.
• Use WakuRelay.getPeers in web chat app example to disable send button.

Changed

• Enable passing strings to addPeerToAddressBook.
• Use addPeerToAddressBook in examples and usage doc.
• Settle on js-waku name across the board.
• Breaking: RelayDefaultTopic renamed to DefaultPubsubTopic.